Method of, and apparatus for, burn-fitting wooden gun stocks to metal receivers

ABSTRACT

Method of, and apparatus for, fully seating on a receiver end the ends of tangs on a wooden gun stock, of which the stock tangs are partially interprojected with receiver tangs on the receiver end, and have excess wood interfering with their full interprojection with the receiver tangs, with the partially interprojected receiver and stock being placed in a holding fixture, and only part of the held receiver therein, including its end, being subjected to high-frequency induction heating to stock-burning temperature, whereupon the stock is driven into full interprojection with the held receiver to the extent of a complete burn-fit of the stock tang ends with the receiver end.

United States Patent Morris et a1.

[ METHOD OF, AND APPARATUS FOR,

BURN-FITTING WOODEN GUN STOCKS TO METAL RECEIVERS [72] Inventors:Stephen J. Morris, North Haven; James M. OKeefe, Cheshire, both of Conn.

[73] Assignee: The Marlin Firearms Co., North Haven, Conn.

[22] Filed: June 4,1971

21 Appl.No.:149,904

[56] References Cited UNITED STATES PATENTS 1,382,852 6/1921 Pittman..2l9/5O X [451 Oct. 10,1972

2,991,548 7/1961 l-lenry ..42/75 C X 1,035,427 8/1912 Donoghue ..144/313X 2,374,706 5/1945 Saslow ..219/10.43

Primary Examiner-R. F. Staubly Assistant Examiner-B. A. ReynoldsAtt0rney-Wa.1ter Spruegel [S 7] ABSTRACT Method of, and apparatus for,fully seating on a receiver end the ends of tangs on a wooden gun stock,of which the stock tangs are partially interprojected with receivertangs on the receiver end, and have excess wood interfering with theirfull interprojection with the receiver tangs, with the partiallyinterprojected receiver and stock being placed in a holding fixture, andonly part of the held receiver therein, including its end, beingsubjected to high-frequency induction heating to stock-burningtemperature, whereupon the stock is driven into full interprojectionwith the held receiver to the extent of a complete burn-fit of the stocktang ends with the receiver end.

10 Claims, 7 Drawing Figures PATENTEMBI 10 I912 3.691.715

SHEET 1 0F 2 PATENIEMBT 10 I972 SHEET 2 OF 2 METHOD OF, AND APPARATUSFOR, BURN- FITTING WOODEN GUN STOCKS TO METAL RECEIVERS This inventionrelates to fitted gun stocks and receivers in general, and to a methodof, and apparatus for, fitting stocks to receivers in particular.

The present invention is concerned especially, though not exclusively,with a widely used type of rifle of which the receiver and stock have,for their firm and lasting mount on each other, interprojected andlocked tangs and also backing shoulders for the ends of theinterprojected tangs. A fairly good fit of the interprojected tangs isbut one of the requirements of a rifle of attractive appearance and goodworkmanship, but a particularly accurate fit between the tang ends andtheir backing shoulders is imperative for additional high functionalquality, in that these shoulders must seat the receiver on the stockwith that accuracy at which the latter will evenly take up all recoilshock and thus obviate any possibility of stock splitting. While afairly good fit of the interprojected tangs may be obtained, either byminimal and relatively simple handfitting of the machined stock tangs tothe receiver tangs, or by machining the stock tangs to dimensions atwhich they adequately interfit with receiver tangs without anyhand-fitting, the backing shoulders will not afford the requiredaccurate seats for receivers without additional stock fitting.

Accurate fitting of wooden parts to metal parts by burn-on of the latterto the former is an old expediency, for example in fitting woodenhandles to the stems of metal tools by heating the stems and rammingthem into undersized holes in the handles. This expediency has also beenresorted to in the gun art in interfitting stocks and receivers of thedescribed type. Thus, there is known a method of burning at least intothe ends of stock tangs the backing shoulders on receivers which are tobe seated thereon sufficiently to provide for the receivers seats of therequired accuracy on the stocks. This prior method involves bringing areceiver to heat in a furnace and placing a stock in a fixture, thenremoving the hot receiver from the furnace and placing it into thefixture in line with the stock therein, and finally driving the stockagainst the receiver for burn-in of at least the receiver seats on thestock. However, while this prior method is entirely satisfactory inaccurately fitting stocks to receivers, the steps involved do not lendthemselves to fitting stocks to receivers at even moderately highmass-production efficiency. Thus, while a number of receivers may bekept in the furnace at the proper heat to have them available for theirfitting with stocks in quickest possible succession, their transfer fromthe furnace into the fixture with a hand tool is a tedious andpotentially hazardous task in any event. Also, the cautious transfer ofhot receivers from the furnace into the fixture will inevitably entailsome cooling of the receivers before their burn-in on stocks, whereforethe receivers are in the furnace overheated for the purpose ofcompensating to some extent for the heat loss in their transfer to thefixture. However, due to uncontrollable and also variable factorsinvolved in the cooling off of the receivers in their transfer to thefixture, it is apparently impossible to have the receivers, at the timeof burn-in, at the exact required heat for adequate burn-in on the onehand, without excessive charring of the wood on the other hand, becausefor successful pursuance of the method the heat in the receivers at thetime of burn-in is kept at a level at which excessive charring of thewood would be inevitable. It is for this reason, and because excessivecharring of the wooden stocks on burnin of the receivers is intolerable,that this prior method further involves the additional step of coatingthe stock portions to-be-burned with a char-retarding compound tocontrol the charring action on burn-in, and preferably also cooling thereceivers immediately after burn-in to stop possible continued charringaction on the stocks.

It is a primary object of the present invention to devise a burn-in typemethod of fitting gun stocks to receivers at very much higherefficiency, including fewer steps and lower cost, than can be achievedwith the aforementioned prior method, with the fit obtained 7 betweenthe stocks and receivers being equally accurate as with the priormethod.

It is another object of the present invention to devise a burn-in typemethod of fitting gun stocks to receivers, in which a cold receiver isplaced in a fixture, then heat is applied, not to the entire receiver,but only to a localized portion thereof best suited for most effectiveheatup of the tangs thereon, and in such manner that the tangs come upto heat, not only to a readily controlled level at which burn-in isentirely adequate for accurate seating fit of the stock on the receiver,yet charring of the wood is negligible and entirely tolerable, but alsoso rapidly that the non-heated remainder of the receiver remainsabsolutely cold, whereupon a tanged stock is driven into seating fitwith the receiver in the fixture. When heat is thus applied to thereceiver, the same is already held in the fixture in position fordrive-on of a stock, and all that remains for burn-in is driving a stockinto seating fit with the receiver the moment its tangs come up to heatof the controlled level, thereby easily accomplishing that adequateburn-in with no more than negligible charring of the wood for which thecontrolled heat level of the receiver is set. Further, the also featuredlocalized heating of the receiver affords in the large cold remainder ofthe receiver a highly effective heat sink which draws heat from thereceiver tangs and, hence, away from the wood after burn-in,sufficiently rapidly to avoid continuing charring of the wood, whereforethe stock and receiver may after burn-in, remain in their seating fitwithout requiring any external cooling of the receiver. Finally, themethod neither requires, nor provides for, the application of anycharretarding agent to the wooden stock.

It is a further object of the present invention to devise a burn-in typemethod of fitting gun stocks to receivers in which the aforementionedlocal and rapid heating of a receiver to a readily controlled level isachieved by high-frequency induction heating, and more particularly byinduction-heating elements in preferred coil form. Thus, suchinduction-heating elements are easily so sized and shaped, and alsolocated in such fixed position relative to the receiver-holding fixture,as to define on a receiver in the fixture a desired and rather sharplydelineated area which will be heated on applying high-frequency currentto these heating elements. Further, heating in this manner of thedesired local area of a receiver in the fixture to the desiredcontrolled level is achieved in a matter of seconds, and once apreferred heat time cycle for a receiver has been determined, it iseasy, in the pursuance of the method, to hold all successive heat timecycles to the preferred time cycle with, or even without, automatictimer interruption of each cycle.

Another object of the present invention is to devise a burn-in typemethod of fitting gun stocks to receivers, of which the machined tangson the stocks are, by preference, so oversized in part as to permittheir partial interprojection with the tangs on receivers before heat-upof the latter, whereby a preferred method further provides for partialassembly to that extent of a stock and receiver, and then placement ofthe partiallyassembled stock and receiver into the fixture forsuccessive heat-up of the receiver and burn-in of the stock. Thus, byselecting, in the machining of the tangs on stocks, the longitudinalextent of their oversized portions, there is afforded a choice forburn-fitting the opposite sides of the tangs on a stock to the oppositesides of the tangs on a receiver either over a very small extent oftheir length or to any greater lengthwise extent, at any extend of whichadequate seats for the receiver are burned in the stock. Further, inthus partially preassembling stocks and receivers, the stocks are withtheir tangs already partly interprojected with the tangs on thereceivers before heat-up of the latter, so that the subsequentfinish-drive of the stocks for burn-in by the receivers in timewise verybrief and is also under effective guidance by the interprojected tangs.Of course, fitting stocks to receivers in accordance with this preferredmethod is made possible in the first place by heating the receivers withthe aforementioned highfrequency induction elements which, while heatingthe receivers, will not heat any parts of wooden stocks within theheating field ofthese elements.

It is another object of the present invention to devise a burned-in typemethod of fitting gun stocks to receivers in which, in placing theaforementioned partially assembled receiver and stock into the fixture,the opposite sides of the receiver remain exposed, and thehigh-frequency induction heating elements are in the preferred form ofopposite spaced coils which flank the placed receiver on its oppositesides over an area which includes, or is largely confined to, the end ofthe receiver from which the tangs projects. Thus, with the receiverbeing customarily of minimum thickness across its opposite sides, theflanking coils will rapidly and evenly bring the receiver up to burn-inheat throughout its affected local mass, including the end shoulders onthe receiver and the tang formation therebeyond for their adequate burninto the stock into seating fit therewith on the finish-drive of thestock into the receiver. Further, in thus placing a partially assembledreceiver and stock into the fixture, the very part of the receiverwhich, on being heated, would burn a grasping hand, is by the flankingcoils sufficiently inaccessible to compel an attendant to remove afinished receiver and stock assembly from the fixture by safely graspingthe far more readily accessible stock.

Further objects and advantages will appear to those skilled in the artfrom the following, considered in conjunction with the accompanyingdrawings.

In the accompanying drawings, in which certain modes of carrying out thepresent invention are shown for illustrative purposes:

FIG. 1 is a side view, partly in section, of a partially assembledreceiver and stock;

FIG. 2 is a fragmentary bottom view of the partially assembled receiverand stock as seen in the direction of the arrow 2 in FIG. 1;

FIG. 3 is a side view, partly in section, of the same receiver and stockfully assembled;

FIG. 4 is a fragmentary section through the receiver and stock takensubstantially on the line 4-4 of FIG. 3;

FIG. 5 is a fragmentary top view of apparatus for assembling thereceiver and stock;

FIG. 6 is a fragmentary side view of the same apparatus as seen in thedirection of the arrow 6 in FIG. 5; and

FIG. 7 is an enlarged section through a modified element of theapparatus.

Referring to the drawings, and more particularly to FIGS. 1 and 2thereof, the reference numerals 10 and 12 designate a metal receiver anda wooden gun stock which have tangs 14 and 16, respectively. Thereceiver 10, being in this instance a steel forging, has a seating end18 from which the spaced receiver tangs 14 extend, and the stock has aseating end 20 from which the stock tangs 16 extend. For a firm andsecure mount of the receiver 10 on the stock 12, the receiver tangs l4and stock tangs 16 are interprojected, and the ends 22 and 24 of thereceiver and stock tangs 14 and 16 are to butt against the seating ends20 and 18 of the stock 12 and receiver 10, respectively. Customarily,the tangs 16 are machined on the stock 12 so as to be interprojectablewith the receiver tangs 14 only partially at the most. In the presentinstance, the stock tangs 16 are machined so as to be readilyinterprojectable with the receiver tangs 14 to the partial extent shownin FIGS. 1 and 2, i.e., the stock tangs 16 are machined to fairly fitwith the receiver tangs 14 over the extent of their readyinterprojectability, but the stock tangs 16 are over an endlength 1thereof oversized so as interfere with full interprojection of the stocktangs with the receiver tangs (FIG. 2). Thus, the ends 24 of the stocktangs 16, which are to rest on the seating end 18 of the receiver, arein this instance oversized by being square and, hence, will not fit theradius formations 26 between the receiver seating end 18 and thetherefrom extending tangs 14 (FIG. 2), and in this instance alsoprojecting tongues 28 on the stock tang ends 24, which are to extend andfit in a recess 30 in the receiver, are oversized by being leftsufficiently thick to interfere with their entry into this recess 30.

The exemplary partially-interprojected receiver and stock are to befully interprojected according to a featured method of the invention,which involves burning away the excess wood on the stock whichinterferes with full interprojection of the latter with the receiver tothe extent of burning at least the seating end 18 of the receiver intouniform and accurate fit with the stock tang ends 24, while forcing thestock into full in terprojection with the receiver. To this end, only apart of the receiver, including the surfaces thereof for burning awaythe excess wood on the stock, is subjected to high-frequency inductionheating, with the subjected receiver part coming very quickly towood-burning temperature, whereupon the stock is forced into fullinterprojection with the receiver to the extent of bringing the endtongues 28 on the stock tangs 16 into full register and burn-fit withthe receiver recess 30, and burning the seating end 18 of the receiverinto uniform and accurate fit with the stock tang ends 24.

The method is practiced in preferred and also featured apparatus 34(FIGS. 4 and 5), which comprises a fixture 36 for removably holding apartially interprojected receiver and stock, a high-frequency inductionheating unit 38, and a stock driving ram 40. The fixture 36 includesfixed brackets 42, 44, 46 and 48 on a table or other support 50, ofwhich bracket 42 provides a rest surface 52 against which the receiveris to bear with its other end 54, and from which extends a dowel pin 56which is to project into an aperture 58 in the receiver. Bracket 44 hasa groove 60 of which the opposite side walls 62 and 63 straddle thereceiver on its opposite side faces 64 and the lower side wall 63 servesas a bottom rest, and the bottom wall 66 of the groove serves as a backstop for the nearby side edge 68 of the receiver. The bracket or post 46has an adjustable screw 70 of which the head 72 serves as a bottom restfor the stock, and the bracket 48 carries an adjustable screw 74 ofwhich the head 76 serves as a back stop for the stock. Pivoted at 78 tothe bracket 42 is a gate 80 having spaced lugs 82 which, in the closedfull-line gate position, straddle the receiver. Thus, with the gate 80in its open dotted-line position (FIG. 5), a partially interprojectedreceiver and stock 10, 12 may laterally be placed into a fixed positionin the fixture 36, by passing the receiver into the groove 60 in bracket44 and placing the stock onto the bottom rest 72, then shifting thereceiver with its aperture 58 into register with the dowel pin 56 andwith its end 54 into butting engagement with the rest surface 54 onbracket 42, and finally thrusting the receiver and stock against theback stops 66 and 76. The partially interprojected receiver and stockare then accurately positioned in the fixture 36. Of course, lateralintroduction or placement of a partially interprojected receiver andstock into the fixture in this or a similar manner is accomplished withhardly any skill and virtually instantaneously in a single-motionmanipulation of the receiver and stock by an operator. With a receiverand stock thus placed in the fixture, the gate 80 may be closed foradditional location of the receiver and stock.

The high-frequency induction heating unit 38 may be of any commercialavailable type, such as one manufactured by Lepel High FrequencyLaboratories, Inc., in New York City, for example. The exemplary unit 38has provisions for converting AC from a commercial power line to a highfrequency suitable for induction heating, and this unit includes in thisinstance at least one pair of spaced load or heating coils 84 and 86which are interconnected, and by leads 88 and 90 connected with thehigh-frequency current source in the unit 38. The interconnected coils84 and 86 are usually made of copper tubing through which water oranother suitable cooling medium is customarily circulated in operationof the coils. The heating coils 84 and 86 are spaced for unimpededpassage therebetween of a partially interprojected receiver and stockinto and also from the fixture 36 (FIG, 6), and they are shaped andlocated to flank, and thereby bring within their heating field, only apredetermined part, including the seating end 18, of the positionedreceiver (FIGS. 5 and 6). The unit 38 is in this instance connected witha commercial AC line L through leads 92 and 94 (FIG. 6).

The stock driving ram 40 is reciprocable to and from the end of thepositioned stock 12 in the fixture 36, and

is to this end movable in a guideway provided by gib plates 96 on thetable 50. The ram 40 is normally urged into the retracted full-lineposition (FIG. 5) by a spring 98 which bears against a bottom lug 100 onthe ram. Cooperating with the ram 40 is a piston 102 in a preferablydoubleacting cylinder 104 on the table 50. Thus, on admitting fluidunder pressure to one end of cylinder 104 and simultaneously venting theother end, the piston 102 is in its retracted position (FIG. 5) in whichthe ram 40 is also in its retracted position. Conversely, on admittingfluid under pressure to the other cylinder end and simultaneouslyventing the one cylinder end, the piston 102 will advance from itsretracted position and thereby move the ram 40 toward the stock 12.Admission of fluid under pressure to either cylinder end andsimultaneously venting the other cylinder end is in this instance undercontrol of a manual valve (not shown).

There is also provided a suitable control for the highfrequencyinduction heating unit 38, which includes, in this example, a switch 106and a presettable timer 110. Switch 106, which is provided in the lead94, is an exemplary snap-type switch which is provided in the lead 94,is an exemplary snap-type switch which is manually closed and is openedby a relay 112 when energized. Relay 112 is in a timer circuit, andopens switch 106 when this circuit is closed. The timer circuitcomprises in this instance a lead 116 from one side of the power line Lto the pointer p of the timer 110, an adjustable contact c on the timer,a lead 118, relay 112, and a lead 120 to the other side of the powerline L. The gradua tions on the timer denote seconds, with the pointer pbeing shown aligned with the 0" second graduation, and the timer contact0 being in this instance set in alignment with the 7 second graduation.The timer circuit is closed, and hence switch 106 opened by relay 112,when in operation of the timer 110 the clockwise moving pointer pengages the timer contact 0, with the pointer p thereupon immediatelyreturning to the 0" graduation to open the timer circuit. The operationof the timer 110 is further such that its pointer p will start itstime-cycle motion from the 0 graduation the moment switch 106 ismanually closed for applying AC from the line L to the unit 38 untilswitch 106 is opened on the explained momentary closure of the timercircuit. Thus, on each manual closure of the switch 106, the time-cycleoperation of the high-frequency induction heating unit 38, includingcoils 84 and 86, is an exemplary 7 seconds.

In pursuance of the featured method, a partially interprojected receiver10 and stock 12 are placed in the fixture 36 in explained manner,whereupon switch 106 is manually closed for a time-cycle performance, ofexemplary seven-second duration, of the high-frequency induction heatingunit 38, including its coils 84 and 86. During this brief time cycle,the affected part of the receiver 10, including its seating end 18 andnearby part of its recess 30 (FIG. 2), comes quickly up to heat, and atthe end of the time cycle is at adequate heat for burn-fitting the stockto the receiver. Thus, the moment the time cycle is concluded, theaforementioned valve is manipulated for immediate advance of the piston102 and ram 40, in the course of which the stock 12 is fullyinterprojected with the receiver 10 to the extend of burn-fitting theend tongues 28 on the stock tangs in the receiver recess 30 and fullyburn-seating the stock tang ends 28 on the receiver seating end 18(FIGS. 3 and 4). To insure an entirely uniform and accurate fit betweenthe receiver seating end 18 and the stock tang ends 24, the burn of theformer into the latter is preferably such that the receiver seating end18 forms a distinct impression i in the stock tang ends 24 (FIG. 4),with the advance of the ram 40 being to this end preferably stopped inthe dotted-line position (FIG. 5) by a suitable stop (not shown). Theram 40 may then immediately be spring-retracted on manipulation of thedescribed valve for retraction of the piston 102, whereupon the fullyinterprojected receiver and stock are removed from the fixture 36,preferably and by far most conveniently by grasping the readilyaccessible and cold stock remote from the heating coils 84, 86 and thestill hot receiver part therebetween.

While in the pursuance of the method just described, burn-in of thereceiver on the stock is readily controlled to bring the receiver tangends 22 into fair fit with the stock seating end 20 (FIG. 4) withoutheating these tang ends 22, it is also feasible to dispense with thementioned ram stop and, instead, let the receiver tang ends 22 act as astop for the advancing ram 40 when the stock seating end 20 comes tobear against, and hence is in good and sightly fit with, the receivertang ends 22. The thus butting stock seating end 20 and receiver tangends 22 (FIG. 4) afford entirely adequate bearing area to withstand thedriving force of the ram 40 which is controlled by the controlledpressure of the operating fluid in the cylinder 104. Thus, in machiningthe tangs l6 and seating end 20 on stocks they may readily be keptwithin tolerances at which, on full interprojection, according to themethod, of a receiver and stock to full butting engagement between stockseating end and receiver tang ends, the receiver seating end 18 isburn-fitted to the stock tang ends 24 to the same or similar extent asin FIG. 4.

In the pursuance of the method, it is also entirely feasible to applythe ram 40 with its driving force to the end of the stock during atime-cycle performance of the I high-frequency induction heating coils84 and 86, say two seconds before the end of the exemplary 7-secondcycle. The ram 40 may thus be advanced to its dot-anddash line position(FIG. 5) in which it is stopped from further advance by the stock 12until the coil-affected receiver part has reached the required burn-intemperature, even before the end of the time cycle, whereupon the ramwill immediately advance further and fully interproject the receiver andstock to the extent of burn-fitting the receiver seating end to thestock tang ends. In so doing, the ram functions fully to interprojectthe receiver and stock independently of, and even before, the set end ofthe time cycle, and also at minimum temperature of the heated receiverpart at which adequate burn-in of the receiver on the stock will takeplace. Moreover, the independent advance motion of the ram 40 for fullinterprojection of the receiver and stock could, if desired, be utilizedto activate a limit switch (not shown) in the line connection with theunit 38 for interruption of the time cycle.

In the pursuance of the method, several important advantages aresecured. Thus, in subjecting only a localized mass of a receiver,including its burn-in surfaces, to high-frequency induction heating, theaffected localized receiver mass will come up to burning heat withcharacteristic rapidity, i.e., in a matter of seconds, and the remaininglarge mass of the receiver remains entirely cold which, therefore, actsas a highly effective heat-sink rapidly to draw heat away from theheated receiver mass and, hence, away from the burn-fitted wood of thestock. Further, with the receiver and stock being already in position inthe fixture for their full interprojection before heat-up of thelocalized part of the receiver, heat-up of the latter may be stopped atthe lowest temperature at which, on immediately following fullinterprojection of the receiver and stock, the former will become fullyburn-fitted with the latter with only negligible charring of the thusfitted wood of the stock. In this connection, numerous receivers havethus been burn-fitted with complete accuracy to stocks at temperaturesof the heated receiver parts of from 600 to 650 F, and the charring ofthe affected wood of the stocks was negligible and entirely tolerableand did not in the least mar the beautiful appearance of the finishedstocks, neither did it in any way weaken the firm seat of the receiveron the stock and its ability safely to withstand recoil shock on firingthe guns. Many of the receivers were thus locally heated to within theabove range of from 600 to 650 F during the. aforementioned exemplarytime cycle of seven seconds. Of course, receivers may be, and have been,locally heated above 650 F and for more or somewhat less than 7 seconds,and their burn-fit with stocks was entirely satisfactory. Generally, andfor high efficiency of the operation, the heating cycle is preferablykept below 10 seconds. Also, local heat-up of receivers is preferablynot to exceed 700 F to insure satisfactory burn-fit with stocks withonly negligible and entirely tolerable charring of the affected wood ofthe stocks. It has been found that, in order to achieve this, thereceivers should be heated anywhere from approximately 600 to 700 F atthe most, for at temperatures slightly above 700 F the operationdeteriorated quite rapidly. Also, such negligible charring of theaffected wood of the stocks as takes place on burn-fitting the receiversthereto, stops with the full interprojection of the receivers and stock,for the described heat-sink effect of the extensive cold mass of thereceivers prevents continued charring of the affected wood, whereforefully interprojected and burn-fitted receivers and stocks need not beseparated, neither need the receivers be artificially cooled, for thepurpose of avoiding any continuing charring of the affected wood.

The high-frequency induction heating unit 38 includes, in this instance,a second pair of spaced heating coils and 132 which flank thefixture-held stock in the vicinity of the ends of the receiver tangs l4,and are designed to heat the latter, though to a lower temperature than.the other heated receiver part, including its seating end 18, because ofthe large interference of the wooden stock between the coils 130, 132and the metal receiver tangs within their heating field. The thus moremoderately heated receiver tang ends lend themselves to a heat andpressure fit, but not burn-fit, with the stock seating end 20 on fullinterprojection of the receiver and stock.

Should it be desired to also burn-fit the receiver tang ends 22 to thestock seating end 20, the latter is provided with sufficient excess woodto that end, and the receiver tang ends 22 are brought more intenselyinto the heating field of the coils 130 and 132 by deforming the latterlike or similarly as in FIG. 7. Thus, front lengths 134 and 136 of thecoils 130 and 132, between which a receiver and stock are laterallyplaced into and removed from the fixture, are extended further forwardlyto bring the exposed receiver tang end 22 therebetween more effectivelywithin their heating field, while rear lengths 138 and 140 of the coils130 and 132 are for the same purpose brought closer to the exposedadjacent receiver tang end 22.

While excess wood of the exemplary stock 12, which interferes with fullinterprojection of the stock and receiver, is confined to a relativelyshort endlength of the stock, it is, of course, fully within the purviewof the present invention to provide stocks with excess wood over alarger endlength thereof to permit initial partial interprojection ofsuch stocks with receivers to a lesser extent than in FIGS. 1 and 2,with the described method being as fully applicable for fullinterprojection and burn-fit stocks with receivers. It is also entirelyfeasible to apply the method, if desired, to fully interproject andburn-fit stocks with receivers, of which the excess or interference woodof the stocks extends over the entire length of the machined stock tangsso that initial interprojection of receivers and stocks is possible onlyto a slight extent, or not at all. In that case, a receiver in thefixture may locally be heated to the required burn-in temperature,whereupon in the absence of the ram 40 and cylinder 104, a stock may bedriven onto the receiver in any suitable manner.

What is claimed is:

1. Method of fitting a wooden gun stock to a seat on a metal receiver,which comprises forming on the stock a counter seat of the approximateshape of the receiver scat but with the wood thereof left to interferewith uniform seating of the counter seat on the receiver seat, placingthe cold receiver in a holding fixture, subjecting only a part of thefixture-held receiver, including its seat, to high-frequency inductionheating, terminating the induction heating of said part of thefixture-held receiver when the remainder of the receiver is still coldand the receiver seat reaches a temperature for complete burn-fit withthe wooden counter seat, and while said receiver part is substantiallyat said burn-fit temperature and said remainder of the receiver is stillcold, forcing the stock with its counter seat against the heated seat onthe fixture-held receiver into complete burn-fit therewith.

2. Method of fitting for interprojection a tanged gun stock to a tangedreceiver, with the receiver having seats for the ends of the stock tangsand the stock tangs having excess wood interfering with fullinterprojection of the respective tangs to the receiver seats, whichcomprises placing the cold receiver in a holding fixture, subjecting tohigh-frequency induction heating a part only of the fixture-heldreceiver, including its seats and the portions of its tangs which holdthe stock tangs with their ends out of complete fit with the receiverseats, terminating the induction heating of said part of thefixture-held receiver when the remainder of the receiver is still coldand the receiver seats and tang portions reach a temperature forburn-off of the interfering excess stock wood and complete burn-fit ofthe ends of the stock tangs with the receiver seats, and while saidreceiver seats and tang portions are substantially at said burn-off andburn-fit temperature and said remainder of the receiver is still cold,fully interprojecting the stock tangs and the heated tangs on thefixture-held receiver to complete burn-fit of the stock tang ends withthe receiver seats.

3. Method of fitting for interprojection a tanged gun stock to a tangedreceiver, with the receiver having seats for the ends of the stock tangsand the stock tangs having excess wood permitting partialinterprojection of the respective tangs but interfering with their fullinterprojection to the receiver seats, which comprises partiallyassembling the cold receiver and stock by partially interprojectingtheir tangs, placing the partially assembled receiver and cold stock ina holding fixture, subjecting to high-frequency induction heating a partonly of the fixture-held receiver, including its seats and the portionsof its tangs which hold the stock tangs with their ends out of completefit with the receiver seats, terminating the induction heating of saidpart of the fixture-held receiver at the end of a period of inductionheating of the same when the remainder of the receiver is still cold andsaid receiver seats and tang portions reach a temperature for burn-offof the interfering excess stock wood and complete burn-fit of the endsof the stock tangs with the receiver seats, and while said receiverseats and tang portions are substantially at said burn-off and burn-fittemperature and said remainder of the receiver is still cold, fullyinterprojecting the partially interprojected tangs on the fixture-heldstock and heated receiver to complete burn-fit of the stock tang endswith the receiver seats.

4. Method as in claim 3, in which the wood burn-off temperature of thereceiver seats and tang portions in within a range from approximately600 F to approximately 700 F.

5. Method as in claim 3, in which the partially interprojected tangs arefully interprojected by applying to the fixture-held stock a forcethrusting the same against the fixture-held receiver.

6. Method as in claim 3, in which the partially interprojected tangs arefully interprojected substantially at the end of said period.

7. Method as in claim 5, in which said force is applied to the stockprior to the end of said period and maintained thereon until completeburn-fit of the stock tang ends with the receiver seats is achieved.

8. Method as in claim 3, in which said period is less than 10 seconds.

9. Method as in claim 3, in which the stock has seats for the receivertang ends, and the partially interprojected tangs are fullyinterprojected to complete burnfit of the stock tang ends with thereceiver seats and rest of the receiver tang ends on the stock seats.

10 Method as in claim 3, in which the stock has seats for the receivertang ends, said receiver tang ends are also included in the receiverpart which is subjected to high-frequency induction heating, and thepartially interprojected tangs are fully interprojected to completeburn-fit of the stock tang ends and receiver tang ends with the receiverseats and stock seats, respectively.

1. Method of fitting a wooden gun stock to a seat on a metal receiver,which comprises forming on the stock a counter seat of the approximateshape of the receiver seat but with the wood thereof left to interferewith uniform seating of the counter seat on the receiver seat, placingthe cold receiver in a holding fixture, subjecting only a part of thefixture-held receiver, including its seat, to high-frequency inductionheating, terminating the induction heating of said part of thefixtureheld receiver when the remainder of the receiver is still coldand the receiver seat reaches a temperature for complete burn-fit withthe wooden counter seat, and while said receiver part is substantiallyat said burn-fit temperature and said remainder of the receiver is stillcold, forcing the stock with its counter seat against the heated seat onthe fixture-held receiver into complete burn-fit therewith.
 2. Method offitting for interprojection a tanged gun stock to a tanged receiver,with the receiver having seats for the ends of the stock tangs and thestock tangs having excess wood interfering with full interprojection ofthe respective tangs to the receiver seats, which comprises placing thecold receiver in a holding fixture, subjecting to high-frequencyinduction heating a part only of the fixture-held receiver, includingits seats and the portions of its tangs which hold the stock tangs withtheir ends out of complete fit with the receiver seats, terminating theinduction heating of said part of the fixture-held receiver when theremainder of the receiver is still cold and the receiver seats and tangportions reach a temperature for burn-off of the interfering excessstock wood and complete burn-fit of the ends of the stock tangs with thereceiver seats, and while said receiver seats and tang portions aresubstantially at said burn-off and burn-fit temperature and saidremainder of the receiver is still cold, fully interprojecting the stocktangs and the heated tangs on the fixture-held receiver to completeburn-fit of the stock tang ends with the receiver seats.
 3. Method offitting for interprojection a tanged gun stock to a tanged receiver,with the receiver having seats for the ends of the stock tangs and thestock tangs having excess wood permitting partial interprojection of therespective tangs but interfering with their full interprojection to thereceiver seats, which comprises partially assembling the cold receiverand stock by partially interprojecting their tangs, placing thepartially assembled receiver and cold stock in a holding fixture,subjecting to high-frequency induction heating a part only of thefixture-held receiver, including its seats and the portions of its tangswhich hold the stock tangs with their ends out of complete fit with thereceiver seats, terminating the induction heating of said part of thefixture-held receiver at the end of a period of induction heating of thesame when the remainder of the receiver is still cold and said receiverseats and tang portions reach a temperature for burn-off of theinterfering excess stock wood and complete burn-fit of the ends of thestock tangs with the receiver seats, and while said receiver seats andtang portions are substantially at said burn-off and burn-fittemperature and said remainder of the receiver is still cold, fullyinterprojecting the partially interprojected tangs on the fixture-heldstock and heated receiver to complete burn-fit of the stock tang endswith the receiver seats.
 4. Method as in claim 3, in which the woodburn-off temperature of the receiver seats and tang portions in within arange from approximately 600* F to approximately 700* F.
 5. Method as inclaim 3, in which the partially interprojected tangs are fullyinterprojected by applying to the fixture-held stock a force thrustingthe same against the fixture-held receiver.
 6. Method as in claim 3, inwhich the partially interprojected tangs are fully interprojectedsubstantially at the end of said period.
 7. Method as in claim 5, inwhich said force is applied to the stock prior to the end of said periodand maintained thereon until complete burn-fit of the stock tang endswith the receiver seats is achieved.
 8. Method as in claim 3, in whichsaid period is less than 10 seconds.
 9. Method as in claim 3, in whichthe stock has seats for the receiver tang ends, and the partiallyinterprojected tangs are fully interprojected to complete burn-fit ofthe stock tang ends with the receiver seats and rest of the receivertang ends on the stock seats. 10 Method as in claim 3, in which thestock has seats for the receiver tang ends, said receiver tang ends arealso included in the receiver part which is subjected to high-frequencyinduction heating, and the partially interprojected tangs are fullyinterprojected to complete burn-fit of the stock tang ends and receivertang ends with the receiver seats and stock seats, respectively.